We show that the use of the real effective exchange rate to test for purchasing power parity, as in Astorga (2012) and other studies, is subject to a problem that biases tests against finding evidence of PPP. The problem is illustrated using Astorga´s data on six Latin American countries.

Empirical evidence regarding the Fisher effect is mixed. One reason may be a nonlinear adjustment process in the real interest rate. The nonlinear unit root test proposed by Sollis, Leybourne, and Newbold (Journal of Money, Credit, and Banking 34: 686-700, 2002) is used to test for stationarity...